This invention relates to vascular catheters for use in percutaneous transluminal angioplasty procedures. In particular, this invention relates to a balloon dilatation catheter for use in percutaneous transluminal coronary angioplasty.
In percutaneous transluminal coronary angioplasty, a guidewire is introduced into a patient's vascular system usually in the femoral artery and advanced to the site of a stenosis in one of the coronary arteries. A balloon dilatation catheter having a balloon at its distal end is then advanced over the guidewire until the balloon is positioned at the stenosis site. The balloon on the catheter is then inflated to exert compression forces against the stenosis. In this manner, the artery can be dilated so a more adequate flow of blood therethrough can be established.
A typical over the wire balloon dilatation catheter comprises an outer tube, an inner tube disposed within the outer tube and extending beyond the distal end of the outer tube and a balloon mounted adjacent to the distal end of the catheter. The proximal neck of the balloon is connected to the outer tube while the distal neck of the balloon is connected to the inner tube. The inner tube defines the guidewire lumen. The annular space between the inner tube and the outer tube defines the inflation lumen and is in communication with the balloon cavity.
In coronary applications, such a balloon dilatation catheter must be pushed a long distance from the body access site to the treatment site. In addition, the catheter must be maneuvered through numerous arterial branches to get to the particular coronary blood vessel where treatment is desired. This requires the balloon dilatation catheter to follow a convoluted and tortuous path. Thus the balloon dilatation catheter must be stiff enough along its proximal portion to allow the catheter to be advanced to the treatment site and yet be flexible enough along its distal portion to follow such a tortuous path. The balloon dilatation catheter must also have a low profile to allow it to be advanced through small coronary arteries and yet have an inflation lumen sufficiently large to allow the balloon to be inflated and deflated quickly.
It would therefore be desirable to provide a balloon dilatation catheter that is flexible enough to negotiate a convoluted and tortuous path through the vascular system yet be stiff enough so it can be pushed through the vascular system.
It would also be desirable to provide a balloon dilatation catheter that has a low profile yet has an inflation lumen that is sufficiently large to allow the balloon to be inflated and deflated quickly.